For years, people in marketing or HR have been sneaking their apps and data onto the cloud, totally bypassing IT's approval or help.

Buckle up, IT.

Those days are coming to an end as more enterprises look into moving critical applications and information to the cloud. IT shops are being called in to corral all of those individual cloud projects, while moving critical data to the cloud, as well.

"Central IT departments are absolutely going to be more involved with how enterprises use, or don't use, cloud services," said Dan Olds, an analyst with The Gabriel Consulting Group. "In the past, individual departments or employees have used cloud services like a fat guy would use a buffet. They'd use whatever service they wanted, when they wanted, and never run their plans by central IT."

Market research firm IDC predicted that the worldwide cloud market, which encompasses private, public and hybrid clouds, will jump from $95.8 billion this year to $118 billion in 2015 and $200 billion by 2018.

The private and hybrid clouds, which will call for IT involvement, should see the strongest growth, according to Technology Business Research. The private cloud is expected to grow 35% year-over-year in 2015 with the hybrid cloud predicted to grow 50%.

It's not such a big deal when departments or individuals want to store simple data on services like Google's Cloud or Apple iCloud for individual projects or even application testing and development.

However, now that bigger, and more important, data stores are going to the cloud, IT needs to be part of the decision-making process, figuring out what cloud service to use and whether the company should use a public, private or hybrid cloud.

"When you're talking about applications and services that are important to the enterprise, it's crucial to have IT in the loop so that they can assess security, performance and availability risk factors," Olds said. "Sort of like having your doctor by your elbow at the buffet. It's not as satisfying, but you'll be healthier in the long run."

Allan Krans, an analyst with Technology Business Research, noted that the days of companies having multiple silos of information and applications running without IT's involvement or knowledge should be coming to an end in the coming year.

It may not be an easy change in the enterprise.

"Individual departments didn't need to manage or integrate or worry about the performance of those workloads," he added. "I think it has created a lot of tension in the enterprise. There was a lot of passive aggressive bypassing of IT. One customer we spoke with said IT had too many barriers to the cloud. First there was security, then it was about politics or simply resisting change."

Since employees have been purposefully bypassing IT with their cloud efforts, there's some resentment and ill feelings there, which will just add to the challenges of working together to build an overall cloud system.

"The teams are not accustomed to working together and implementing change," Krans said. "It's not just a technology problem. It's an organization problem. It's a culture problem. The cloud is exacerbating a problem that's been there all along."

Jeff Kagan, an independent industry analyst, said IT managers shouldn't wait to be invited to the cloud discussion. They should reach out to business executives and explain the benefits, risks and challenges of adopting the cloud and reigning in those rogue cloud users.

"This is both a blessing and a curse for the IT department," said Kagan. "This is very positive for the enterprise if they do this correctly, and if they don't have any security problems along the way. This is the way business will be run going forward. We are in the bumpy transition period, which will take several years."

Part of that transition means IT managers need to bone up on all things cloud before they enter into discussions with business executives. IT executives need to be able to assess the different cloud implementations they'll be asked about and understand the implications of a cloud or no-cloud decision.

IT will also need to develop policies to govern cloud use and mechanisms to make it easy for departments to comply, noted Olds.

"This is a good development because it gives IT visibility into what's actually going on in the rest of the organization," he added. "The fact that departments already are using outside cloud providers will complicate it, for sure. Many computing revolutions started out with disgruntled users rolling their own solutions without the approval or knowledge of central IT. This is just the circle of life in the business-IT ecosystem."